Three-dimensional display devices such as three-dimensional televisions and head-mounted displays that can stereoscopically present video have been used. Devices that can stereoscopically present video in portable terminals such as mobile phones and portable game machines have also been developed and opportunities for general users to view stereoscopic video have been increasing.
The three-dimensional display devices that display stereoscopic video enable the user to stereoscopically view images by causing the right and left eyes of the user to see images with a parallax. There are a system in which special optical glasses are used for causing right and left eyes to see images with a parallax, a system in which a parallax barrier or lenticular lens is used without using optical glasses, and so forth.